/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.jdbc.support;

import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import org.springframework.dao.DataRetrievalFailureException;
import org.springframework.dao.InvalidDataAccessApiUsageException;
import org.springframework.lang.Nullable;

The standard implementation of the KeyHolder interface, to be used for holding auto-generated keys (as potentially returned by JDBC insert statements).

Create an instance of this class for each insert operation, and pass it to the corresponding JdbcTemplate or SqlUpdate methods.

Author:Thomas Risberg, Juergen Hoeller
Since:1.1
/** * The standard implementation of the {@link KeyHolder} interface, to be used for * holding auto-generated keys (as potentially returned by JDBC insert statements). * * <p>Create an instance of this class for each insert operation, and pass it * to the corresponding {@link org.springframework.jdbc.core.JdbcTemplate} or * {@link org.springframework.jdbc.object.SqlUpdate} methods. * * @author Thomas Risberg * @author Juergen Hoeller * @since 1.1 */
public class GeneratedKeyHolder implements KeyHolder { private final List<Map<String, Object>> keyList;
Create a new GeneratedKeyHolder with a default list.
/** * Create a new GeneratedKeyHolder with a default list. */
public GeneratedKeyHolder() { this.keyList = new LinkedList<>(); }
Create a new GeneratedKeyHolder with a given list.
Params:
  • keyList – a list to hold maps of keys
/** * Create a new GeneratedKeyHolder with a given list. * @param keyList a list to hold maps of keys */
public GeneratedKeyHolder(List<Map<String, Object>> keyList) { this.keyList = keyList; } @Override @Nullable public Number getKey() throws InvalidDataAccessApiUsageException, DataRetrievalFailureException { if (this.keyList.isEmpty()) { return null; } if (this.keyList.size() > 1 || this.keyList.get(0).size() > 1) { throw new InvalidDataAccessApiUsageException( "The getKey method should only be used when a single key is returned. " + "The current key entry contains multiple keys: " + this.keyList); } Iterator<Object> keyIter = this.keyList.get(0).values().iterator(); if (keyIter.hasNext()) { Object key = keyIter.next(); if (!(key instanceof Number)) { throw new DataRetrievalFailureException( "The generated key is not of a supported numeric type. " + "Unable to cast [" + (key != null ? key.getClass().getName() : null) + "] to [" + Number.class.getName() + "]"); } return (Number) key; } else { throw new DataRetrievalFailureException("Unable to retrieve the generated key. " + "Check that the table has an identity column enabled."); } } @Override @Nullable public Map<String, Object> getKeys() throws InvalidDataAccessApiUsageException { if (this.keyList.isEmpty()) { return null; } if (this.keyList.size() > 1) { throw new InvalidDataAccessApiUsageException( "The getKeys method should only be used when keys for a single row are returned. " + "The current key list contains keys for multiple rows: " + this.keyList); } return this.keyList.get(0); } @Override public List<Map<String, Object>> getKeyList() { return this.keyList; } }